Terra refers to a satellite that is part of NASA's Earth Orbiting System (EOS). Terra was the first satellite dedicated to monitoring Earth's health on a daily basis.

Terra contains five key instruments that take coincident measurements of the Earth system. These are:[1]

  • Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)
  • Clouds and Earth's Radiant Energy System (CERES)
  • Multi-angle Imaging Spectroradiometer (MISR)
  • Measurements of Pollution in the Troposphere (MOPITT)
  • Moderate Resolution Imaging Spectroradiometer (MODIS).

Terra was first operational in spring of 2000, after it was launched on 18 December, 1999.[1]It has exceeded its initial life expectancy of around 6 years and is considered capable of surviving until the 2020s.[1][2]

Terra is orbiting at a height of 705km and circles the Earth pole to pole.[1]It has an inclination of 98.5 degrees, has 6 orbits each day (each of 99 minutes) and its equatorial crossing occurs at 10:30am, descending node.[1]

The importance of Terra[edit | edit source]

Terra is an important part of increasing our understanding of how the Earth's systems work.[2] This includes reaching better understandings on how the different systems work together.[2]Ultimately, the data and knowledge gained from Terra will help us to predict future changes with greater certainty.

Terra has many sensors that allow scientists to monitor vital signs on Earth. This includes the concentrations of greenhouse gases and changes in their status, the amount of snow, ice and cloud cover (and any changes over time), the flux of radiant energy from the Sun and the changes in the levels of pollutants other than greenhouse gases.[3] Terra can send back information about vegetation cover on land and the growth of plant life in the oceans.[3]It can provide temperature information, from the atmosphere, land and water bodies.[3]

Terra is an important part of the process of providing reliable and credible information to keep scientists and the public informed about climate predictions and changes.[3]

Keeping updated on Terra[edit | edit source]

Visit NASA at http://terra.nasa.gov/about for basic information on the current status of Terra at any given time. A status file in PDF form can be found on this page.

Visit NASA's Terra data page at: http://terra.nasa.gov/data for links to the massive amount of data being sent back weekly. This information is available to any person with an interest and an internet connection. The five instruments produce 79 "core data products" that can be accessed via the Land Processes Distributed Active Archive Center (LPDAAC), the Atmospheric Science Data Center (ASDC), Ocean Color Web, Level 1 and Atmosphere Archive and Distribution System, and the National Snow and Ice Data Center (NSIDC).[4]

See also[edit | edit source]

  • http://terra.nasa.gov/about - general reference page
  • M.D. Kin and D. D. Herring. (2000) Monitoring Earth's vital signs. Scientific American. April, 2000, pp. 92-97

References[edit | edit source]